The present invention relates generally to a device and method of cavitational mixing. However, it finds particular application in both mixing and pumping applications and will be described with particular reference thereto.
Up to the present time, it is well known that there are many chemical reactions that essentially alter the speed and yield of finished products under the influence of ultrasonic oscillation.
There also exists a great quantity of chemical reactions and mixing that may only proceed under the influence of ultrasonic oscillation. Similar reactions may be accomplished in aqueous as well as non-aqueous, liquid-based media. The main requirement for the realization of similar reactions is the imposition of ultrasonic oscillations on the liquid medium. All of these chemical reactions relate to the class of sonochemical reactions. As determined through many years of investigation and numerous research studies (Timothy J. Mason, “Advances in Sonochemistry”, Volume 3. 1993. 292 pp., JAI Press Inc.), the sources of initiation of sonochemical reactions appear as cavitation bubbles which arise in liquid-based media during diffusion within by ultrasonic oscillations.
During the collapse of the cavitation bubbles, very high localized pressures and temperatures are achieved. According to some estimations the temperature within the bubbles attains a magnitude in the order of 5000° C. and pressure of approximately 500 kg/cm2 (K. S. Suslick, Science, Vol. 247, Mar. 23, 1990, pgs. 1439-1445). These high temperatures and pressures stimulate the progress of various chemical reactions such as in the gaseous phase within the bubble as well as in the gaseous phase on the surface of the bubble.
Common for all sonochemical reactions and processes is that, for the creation of cavitation bubbles in a liquid-based medium, the principle of application of ultrasonic oscillations on the liquid-based medium is used. The basic equipment which is used in sonochemistry appear as ultrasonic devices of various designs.
This method of conducting sonochemical reactions is sufficiently effective for processing small volumes of liquids and has found its chief application on the level of laboratory research. Transitioning to large scale volumes, however, which are used in industry, is significantly difficult and even at times impossible. This is associated with the problems which arise during the scaling up of cavitation that is produced with the aid of ultrasonic oscillations.
It is possible to avoid these shortcomings, however, by producing the quality of the initiator of sonochemical reactions, cavitation bubbles, through the course of hydrodynamics. An example of using hydrodynamic cavitation for conducting sonochemical reactions is presented in the work of: Pandit A. B., Moholkar V. S., “Harness Cavitation to Improve Processing,” Chemical Engineering Progress, July 1996, pgs. 57-69.
However, the aforementioned example method of realizing sonochemical reactions with the aid of hydrodynamic cavitation is not effective. As noted by the authors themselves, one of the problems they uncovered was the ineffective utilization of the energy in the hydrodynamic flow. Utilization of non-optimal regimes of hydrodynamic cavitation leads to a decrease in the intensity of sonochemical reactions and increases the degree of heating the medium.
In the present invention, the proposed method of conducting sonochemical reactions and processes, particularly in large scale volumes of liquid-based media, allows the utilization of optimal hydrodynamic cavitation regimes and also reduces the energy consumption for conducting the processes.
The present invention contemplates a new and improved method and apparatus for conducting sonochemical reactions and processes, particularly in large scale volumes of liquid based media, using the optimal hydrodynamic cavitation regimes and reducing the energy consumption for conducting the processes, which is simple in design, effective in use, and overcomes the foregoing difficulties and others while providing better and more advantageous overall results. Specifically, the present invention relates to utilizing cavitation in large scale volumes for both mixing and pumping applications.